1. Field of the Invention
The present invention relates to cartridges for extracting a substance from a composition and a process for making the cartridges. Further, the present invention relates to a method for extracting a substance from a composition. More specifically, the present invention relates to a method for extracting a drug from a biological sample so that the drug is extracted with good recovery and without extraneous components that would cause interferences during analysis. Still further, this invention relates to an automatic processing apparatus for extracting substances from a composition.
2. Discussion of Background Information
One of the main areas of activity of pharmaceutical companies, contract research laboratories and medical laboratories is the determination of drug levels in samples of human and animal complex biological fluids such as blood, plasma, serum and urine. The drugs are usually present in extremely low concentrations and the most sensitive detection devices are required for their quantification. It is therefore necessary that the drug be separated from all other materials present in the complex biological fluids since the other materials could cause interference during analysis. This separation step is generally referred to as the sample preparation step.
The need to extract only the drug from the other components of the complex biological fluid is becoming increasingly important with the development of increasingly sensitive analytical techniques like gas chromotography/electron capture detector (GC/ECD), gas chromotography/nitrogen phosphorus detector (GC/NPD), gas chromotography/mass spectroscopy (GC/MS) and liquid chromotography/mass spectroscopy (LC/MS). These methods allow drug detection at the low nanogram/ml and even picogram/ml levels.
Extraction of drugs from biological fluids is presently achieved by one of three procedures: liquid-liquid extraction, solid phase extraction and liquid-liquid extraction on a solid phase support, called Thin-Film Liquid-Liquid Extraction. Each of these procedures will be briefly described.